137
Turns out all we may need to stop climate change is 139 billion gallons of super-duper white paint
(www.businessinsider.com)
This is a most excellent place for technology news and articles.
There is no one solution to climate change, but requiring lighter roofs for all new builds/replacements would be a simple step to start with. It doesn't just increase the amount of light reflected back out to space, but it also significantly reduces cooling requirements, meaning less power required during peak hours.
When it comes time to change my roof, I will be considering lighter shades.